Offshore elevator improvements

ABSTRACT

An offshore elevator structure including an elevator lift guidingly raised and lowered by a drive assembly including a system of cables and capable of floating on the water while maintaining the cables in a substantially taut condition.

United States Patent Donald L. St. Louis Anchorage, Alaska Oct. 10, 1968 Feb. 23, 1971 Alaska Elevator Corporation Anchorage, Alaska a corporation of Alaska [72] Inventor [21 App]. No. [22] Filed [45] Patented [73] Assignee [54] OFFSHORE ELEVATOR IMPROVEMENTS 2 Claims, 3 Drawing Figs.

[52] U.S. Cl 187 /2 7 114/435: 187/1 1, 187/95 [51] Int. Cl. 1366b 11/04 [50] Field ofSearch 114/435;

[56] References Cited UNITED STATES PATENTS 2,972,973 2/1961 Thearle 254/172 3,300,189 1/1967 Blount.... 254/185 3,318,276 5/1967 Nemec 114/435 Primary Examiner Harvey C. Hornsby Attorney-Strauch, Nolan, Neale, Nies and Kurz ABSTRACT: An offshore elevator structure including an elevator lift guidingly raised and lowered by a drive assembly including a system of cables and capable of floating on the water while maintaining the cables in a substantially taut condition.

PATENTEU FEB2 3 IS?! SHEET 1 [1F 2 INVENTOR. DONALD ST. LOUIS MM fhy/ ATTORNEYS OFFSHORE ELEVATOR IMPROVEMENTS BACKGROUND OF THE INVENTION This invention is generally concerned with improvements in offshore elevator structures and more particularly with an offshore elevator assembly which includes an elevator lift guidingly raised and lowered by a system of cables and capable of floating up and down on the water surface with cables maintained substantially taut during flotation of the lift.

Marine or elevator platforms have been proposed and built using various devices for raising and lowering men and equipment between the ocean level and a fixed upper platform. However, past elevator lifts or platforms have not been used very successfully in extremely rough waters where, for example, the waves may vary in height up to 30 feet. In such waters, the elevator lift upon which people or supplies are to be placed for raising from the water to the fixed upper platform is generally held stationary during the loading operation, while the boat or other vehicle holding the people or supplies is moving up and down on the waves. This, of course, renders it extremely difficult, if not impossible, to transfer the people or supplies from the boat to the elevator lift.

SUMMARY OF THE INVENTION Accordingly, the primary object of this invention resides in the provision of a marine platform assembly including a fixed upper operating platform and a novel lower elevator lift platform guidingly raised and lowered by a system of flexible cables and capable of floating in the water while maintaining the cables substantially taut, thereby permitting ready transfer of people and/or supplies between the lift platform and other vehicles floating on the water.

Another object resides in the provision of a novel, elevator lift platform having the above described cable guide and drive system which includes a drive motor and cable drums and a clutch mechanism through which the cable drums are alternatively positively driven by the motor for raising or lowering the lift platform or permitted to run freely when the lift is floating on the water.

Still another object resides in the provision of a novel cable support and drive system for an elevator lift platform comprising a drive motor, cable drums, and a clutch mechanism through which the drums are alternatively driven by the motor for raising or lowering the platform or permitted to run freely when the lift is floating on the water. Opposite ends of each of a plurality of cables wrapped around the drums are connected to the platform so that the cables remain substantially taut during floating, thereby causing the platform to be immediately raised upon energization of the motor and clutch.

Other objects and advantages of the invention will become apparent from reading the detailed description of a preferred embodiment set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, generally perspective view of a marine platformof the invention including the novel floating platform and its cable guide and drive system;

FIG. 2 is a plan view of the fixed upper operating deck and the cable drive system supported thereon; and

FIG. 3 is a fragmentary elevation view illustrating the manner in which each cable is connected to the lift platform and its associated driving cable drum and idler pulleys.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is illustrated as applied to a marine platform structure which comprises an upper fixed horizontal platform Bil suitably supported above the water surface and carrying all the operational equipment associated with the structure. A vertically movable lower lift platform 12 is provided to raise or lower materials between the upper platform and the water surface 114.

Platform 10 may be supported by a central hollow vertical column secured to the ocean floor l5 and passing centrally through lower platform 12 on which various types of equip ment such as life rafts and boats may be carried. Platform 12 may also be provided with suitable deck areas and guard railing which cooperate with a stairway on the underside of upper platform 10 to assist in the transfer of men and materials between platforms l0 and 12. This general type construction is illustrated in applicants copending application Ser. No. 666,602, on which this invention is an improvement.

Lift platform 12 is adapted to float on water surface 14 and move up and down thereon as the height of the waves varies. Lift platform 12 is guided and positively driven through a cable system including cables l6, 18, 20 and 22 each of which has its ends fixedly connected respectively to the top and bottom of lift 12 and has a fixed operating length and remains substantially taut at all times.

The cables are operated from a drive system 23 suitably supported on upper platform 10 and including electric motor 24 drivingly connected to cable drum shaft 26 through gear reduction box 28, suitable clutch mechanism 30 and bevel gear assembly 32. Clutch mechanism 30 may be of any suitable type, but preferably is an electrically operated clutch having clutching and nonclutching conditions and operated by electrical control assembly 34. A suitable electrical control system 36 is also provided for electric motor 24, and both electrical systems 34 and 36 may be controlled or actuated from lift platform 12. Fixed at each end of shaft 26 are wrench or cable drums 38 and 40, with cables 16 and 18 being driven by drum 38 and cables 20 and 22 by drum 40.

Cables 16, 18, 20, and 22 are symmetrically positioned at respective corners of platform 12 and are vertically parallel to each other. The cables are fixed to lift 12 identically to cable 18 which, as shown in FIG. 3, extends upwardly from fixed connection 52 through slot 41 in platform 10 over deflection idler pulley 42, around cable drum 38 with one or more number of wraps depending upon the desired traction factor, over deflection idler pulley 44 down through slot 45 in platform 10 and aperture 46 in platform 12, around idler pulley 48 fixed to rigid support 50 secured in ocean bed 15, and finally having its other end fixed at 54 to the bottom of platform 12.

Cables 16, 20, and 22 extend through slots identical to slots 41 and 45 around idler pulleys identical to pulleys 42, 44, and 48 and their respective drums with their ends connected to platform 12. Each of the deflection idler pulleys 42 and 44 is rotatable and axially slidably mounted on a fixed axis horizontal idler axle 43 and as the cables helically wind in either direction on their respective drums, the deflection pulleys will travel back and forth along their respective axles and the platform slots such as slots 41 and 45 allow to and fro displacement of the cables. The construction of the idler pulleys and axles is identical to that described in application Ser. No. 666,602.

In this novel cable system the effective operating length of each of the cables is fixed and, as lift 12 floats up and down on water surface 14, the cables remain substantially taut, thereby preventing any substantial horizontal movement but permitting a limited amount of rocking of lift 12 while guiding it for vertical movement.

During operation, when people or supplies are being transferred between a boat in the water and lift platform 12, clutch 30 is retained in a nonclutching condition, thereby rendering shaft 26, bevel gear mechanism 32, and cable drums 38 and 40 free wheeling to permit lift platform 12 to float up and down on the waves of the water along with the boat. When the transfer operation has been completed, motor 24 and clutch 30 are energized through control systems 34 and 36, thereby positively driving drums 38 and 40 in a suitable direction to raise lift 12 from water surface 14 to operating platform 10. Similarly, when platform 12 is to be lowered again, drums 38 and 40 are driven in the opposite direction to lower the platform.

Because the cables 16, 18, 20, and 22 remain substantially taut while drums 38 and 40 are free wheeling and platform 12 is floating, drive system 23 is effective to immediately raise platform 12 upon energization of motor 24 and clutch 30 since there is no slack in the cables to be taken up. This, of course, provides better operational control and quick response of lift platform 12.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

lclaim:

1. An elevator assembly for an offshore marine installation in which a fixed upper platform is mounted above the normal water level of a body of water comprising a lower platform,

drive means comprising drum means mounted on said upper platform, motor means and clutch means selectively providing a drive connection between said motor means and said drum means, a system of cables connecting said drum means to said lower platform for raising and lowering said lower platform, cable support means fixed below the water level, each of said cables extending between said drum means, said support means, and said lower platform and having both ends connected to said lower platform, whereby when said clutch is engaged said lower platform may be driven up or down and. when said clutch is disengaged and said drum means is permitted to run freely, said lower platform may float on said water with said cables being maintained in a substantially taut condition.

2. In the elevator assembly defined in claim 1, each of said cables having one end fixed to said lower platform, the other end extending therefrom around said drum means and said support means and also being fixed to said lower platform. 

1. An elevator assembly for an offshore marine installation in which a fixed upper platform is mounted above the normal water level of a body of water comprising a lower platform, drive means comprising drum means mounted on said upper platform, motor means and clutch means selectively providing a drive connection between said motor means and said drum means, a system of cables connecting said drum means to said lower platform for raising and lowering said lower platform, cable support means fixed below the water level, each of said cables extending between said drum means, said support means, and said lower platform and having both ends connected to said lower platform, whereby when said clutch is engaged said lower platform may be driven up or down and, when said clutch is disengaged and said drum means is permitted to run freely, said lower platform may float on said water with said cables being maintained in a substantially taut condition.
 2. In the elevator assembly defined in claim 1, each of said cables having one end fixed to said lower platform, the other end extending therefrom around said drum means and said support means and also being fixed to said lower platform. 